Processing of a request for data delivery from a server to a client via a telecommunication network

ABSTRACT

Processing a request for delivery of data sent by a customer terminal to a remote server via a telecommunication network. The terminal accesses the network by at least two links of distinct access types. The data is encoded in a stream with a predetermined bit rate, which is cut into segments. Processing includes, for a segment of the stream: determining a sub-segment size based on the number of links and a size of the data stream to be delivered; calculating a partitioning of the segment into sub-segments according to the set size and a distribution of the sub-segments on the plurality of links, according to a scheduling of the sub-segments in the partitioning and a time constraint; and sending a plurality of sub-segment transmission requests to the server over the plurality of links, each request including an identifier of the segment and indexes of a sub-segment start and end.

1. CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Section 371 National Stage Application ofInternational Application No. PCT/FR2015/053216, filed Nov. 26, 2015,the content of which is incorporated herein by reference in itsentirety, and published as WO 2016/083740 on Jun. 2, 2016, not inEnglish.

2. FIELD OF THE INVENTION

The field of the invention is that of the delivery of data from a serverto a client via at least one telecommunication network.

The invention may in particular, but not exclusively, apply to thedelivery of multimedia data streams according to an “http adaptivestreaming” type technology.

3. PRESENTATION OF THE RELATED ART

It is known from the MPEG-DASH (for “Dynamic Adaptive Streaming overhttp”) a technique for delivering multimedia data by a HypertextTransfer Protocol (HTTP) server equipment to a client equipment DASH,wherein multimedia data are cut into segments, which are encoded at aplurality of bit rate values. This technique is described in particularin the article entitled «Dynamic Adaptive Streaming over http-Standardsand Design Principles», by Thomas Stockhammer, published in theProceedings of the «ACM Conference on Multimedia Systems, in February2011, pages 133-144.

In connection with FIG. 1, the customer equipment DASH UE connects tothe server equipment ES via a communication network RT. The serverequipment ES has several data files F1, F2, F3, . . . FN thereforecorresponding to the same segment, encoded at different qualities. Theclient equipment DASH which wishes to receive the multimedia datastreams begins by requesting the server equipment to transmit to it aMPD type description file (for “Media Presentation Description”) of themultimedia data. This file describes in particular the filescorresponding to the segments available at the server equipment andtheir associated data rate. The client uses the description data of thisfile to determine, for each segment, the file that corresponds to thebit rate of his choice, as a function of the bandwidth at a giveninstant and to define the delivery request to be sent to the serverequipment.

A first advantage of this technique is that it is simple. The fact ofbeing based on the http protocol solves the problem of going throughfirewalls and the server equipment consists of a generic WEB server,inexpensive and easy to deploy on a large scale.

A second advantage of this technique is that it is adaptive. The clientequipment adapts its request to the available bandwidth by choosing asegment encoded at a higher or lower bit rate. For example, the clientequipment first requests delivery of high bit rate files for the firstsegments, and then switches to lower bit rate files for subsequentsegments when it encounters a momentary bandwidth problem.

A first shortcoming of this technique lies in the large size of thesegments available at the server, which corresponds, in the case of avideo sequence, to a duration comprised between 3 and 10 seconds. Whenthe network conditions are not optimal, its transmission may be delayedor show a latency which is not compatible with real-time constraints.

A shortcoming of this technique is that it uses http which relies on theTransport Control Protocol (TCP). Such a protocol establishes aconnection between the server equipment and the client equipment andenables the safe transmission of data by an acknowledgment exchange.Nevertheless, this signalling introduces a delay, due to retransmissionsof lost data packets, which precludes the possibility of real timedelivery.

4. SUMMARY OF THE INVENTION

An exemplary aspect of the present invention relates to a method forprocessing a request for the delivery of data sent by a customerterminal to a remote server equipment via a telecommunication network,said terminal being adapted to access said network by at least two linksaccording to distinct access types, said data having been encoded in atleast one stream with at least a predetermined bit rate, said streamhaving been previously cut into a plurality of segments.

The method according to the invention is particular in that it comprisesthe following steps, implemented for a segment of the at least one datastream:

-   -   Determining at least one sub-segment size at least based on the        number of links and a size of the data stream to be delivered;    -   Calculating a partitioning of the segment into sub-segments        according to said at least one set size and a distribution of        the sub-segments on the plurality of links at least in        accordance with a scheduling of the sub-segments in the        partitioning calculated and a predetermined time constraint; and    -   Sending a plurality of transmission requests of the sub-segments        to the server on the plurality of links, at least according to        the distribution calculated, a transmission request of a        sub-segment on a link comprising at least one identifier of the        segment, an index of a sub-segment start and an index of a        sub-segment end.

With the invention, the delivery request of a segment of the data streamis converted into a plurality of sub-requests on each of the linksavailable to access the communication network. The sub-requests relateto one or more sub-segments of smaller sizes than the entire segment.

Thus, the invention relies on a completely novel and inventive approachto the delivery of multimedia data, based, on the one hand, on adecision to cut a segment of data encoded into sub-segments of suitablesize at least according to the number of links available in paralleland, on the other hand, to a distribution of the sub-requests on theselinks.

Requiring sub-segments of smaller sizes than the segment makes itpossible to reduce delivery latency. The involvement of multipleaccesses to the network for the same delivery makes it possible tooptimise the exploitation of available resources and to reduce theoverall delivery time.

An advantage of the invention is that it does not modify the operationsof the network and of the server equipment. In fact, the inventionrelies on a known operation of a web server which enables it to respondto a request for delivery of a chunk of a multimedia data streamcomprising positioning information for this chunk in the file.

According to an advantageous characteristic of the invention, the methodfurther comprises a step of measuring parameters representative of anetwork state on the plurality of links, implemented upon receivingsub-segments from the server on said links in response to thetransmission requests and a step of updating the steps of determining asub-segment size per link and calculating a partitioning and adistribution of the sub-segments on the links according to the measuredparameters.

Following the reception of the first sub-segments on the various links,parameters representative of a network state on these links are measuredand exploited to adapt the size of a sub-segment per link and to refinethe distribution of the requests between the different links.

The measured network parameters are typical of the efficiency of a linkand include, for example, latency, maximum throughput, loss rate andnetwork jitter.

Advantageously, it is possible to assign weights to the links accordingto the calculated network parameters in order to take these weights intoaccount during the step of distributing the sub-segments on the links.

According to another aspect of the invention, the method comprises astep of determining a frequency for transmitting the requests on a linkaccording to the measured network parameters and in that thetransmission requests of the sub-segments on said link are transmittedat the determined transmission frequencies.

This allows the implementation of a burst mode, in which the clientequipment does not wait for the server equipment to respond to a firstrequest on a link to issue another one on the same link, in order not tobe constrained by a sequential mode that would slow down thetransmission of data from a link. The frequency or transmission rate ischosen in an appropriate manner so as not to saturate the network link.

According to another aspect of the invention, the method furthercomprises a step of obtaining an encoding structure comprising at leastone piece of information representative of a type of data encoded in thesegment associated with position information of the data of this type, astep of assigning a decoding priority level to the sub-segments of asegment according to the type information and to predetermined rules,and in that the step of partitioning the segment into sub-segments andthe step of distributing the sub-segments on the plurality of links alsotake into account the levels of decoding priorities assigned to thesub-segments.

An advantage of assigning levels of decoding priorities to thesub-segments is to allow the implementation of a strategy fordistributing the sub-requests on the available links, which favours thehigher-priority sub-segments and the requests on the most reliablelinks. For example, a high decoding priority level is assigned tosub-segments containing encoded data belonging to an Intra (or I) image,because such an image serves as a reference for decoding other images.It is therefore important to ensure its delivery reliably. It isunderstood that this requires obtaining the position information of theboundaries between the images in the sub-segment before requesting thecorresponding sub-segment. This indexing must first be obtained by theclient.

According to another aspect of the invention, the informationrepresentative of a data type is obtained by sending a request fordescription of the segment to the server equipment and by receiving adescription file of an encoding structure of the segment comprising saidinformation.

The MPEG DASH standard has an “On Demand” type profile to allow a clientof a Video on Demand application to move in a segment of a data streamand perform fast-forward functions. The implementation of such functionsrequires indeed to know the structure of the encoded data in order tolocate the positioning of the reference images I and to trigger the hopfrom one image I to another. The description information of the encodingstructure of the segment is contained in a description file of SSIX type(for “sub-segment index”).

The invention advantageously proposes to take advantage of thisdescription information for real-time purposes the better to break asegment down into sub-segments and to distribute them on the variousaccess links to the network.

According to another aspect of the invention, the step of measuringnetwork parameters comprises measuring a latency time between thetransmission of a request for transmission of at least one sub-segmenton a link and the reception of the requested sub-segment and in thatsaid method comprises, in the case of a latency time measured greaterthan a predetermined threshold for said request, a decision step fortriggering an action at least as a function of a priority level ofdecoding assigned to the requested sub-segment, said action belonging toa group comprising at least:

-   -   Retransmission of a new transmission request from the same        sub-segment to another link;        -   Cancellation of the current request.

One advantage is to quickly detect that a transmission problem hasoccurred and decide on a solution to set up for the sub-segments queriedby another link, by minimising the extra time on the overall datadelivery.

The consideration of the priority level of the data for the decoding ofa sub-segment in the distribution of the sub-requests on the availablelinks proposed by the invention makes it possible to limit the damagedue to the possible non-reception of this sub-segment for the subsequentdecoding of the multimedia data, in particular in terms of renderingquality.If the priority level of the sub-segment is low, the action triggeredwill be the plain and simple cancellation of the request. Furtherprocessing of the data will be done without the missing sub-segment. Oneadvantage to cancel a sub-request, rather than leaving its course is toavoid unnecessary signalling and occupation of the associated bandwidth.If, on the contrary, the priority level of the sub-segment is high, thetriggered action is to issue a new request for the same sub-segment onanother link. Both actions can of course be triggered simultaneously.According to another aspect of the invention, the customer terminal andthe server equipment are arranged to communicate according to acommunication protocol with acknowledgment exchange and when the actiondecided is a cancellation of the current request, the method comprises astep of transmitting an acknowledgment message to the server.The aim is to make the server equipment believe that the sub-segment hasindeed been received. This makes it possible to bypass an acknowledgmentmechanism imposed by a communication protocol in connected mode, of TCPtype and to avoid the heaviness.

According to another aspect of the invention, the received descriptionfile further comprises information representative of a data membershipgroup and at least one first encoded data stream being available at afirst bit rate and a second stream at a second bit rate, the methodcomprises a step of selecting a stream in which a sub-segment of thecurrent segment can be requested, at least based on the measured networkparameters, the decoding priority level of the subset of the membershipgroup of data of the sub-segment and the predetermined time constraint.

An advantage is to benefit from each representation or quality of streamavailable at the server to optimise delivery within a segment. Inaddition to an optimisation of the use of resources based on adistribution of the sub-segments on the links available with agranularity finer than the segment, the invention also makes it possibleto adapt in a finer bit rate than the prior art.

Indeed, for a given sub-segment, the data stream with the highestpossible bit rate is chosen, making it possible on the one hand tosatisfy the predetermined time constraint while taking into account themembership group of the data encoded in the sub-segment. For example,this membership group is a GoP comprising an image of type Intra andother images of type P or B which depend on the image I. It isunderstood that the images of the same GoP and therefore thesub-segments must be requested in the same stream. The inventiontherefore makes it possible an Intra by Intra adaptation.

The method which has just been described in its various embodiments isadvantageously implemented by a device for processing a request for thedelivery of multimedia data.

Disclosed is therefore a device for processing a request for thedelivery of data sent by a customer terminal to a remote serverequipment via a telecommunication network, said terminal being adaptedto access said network by at least two links according to distinctaccess types, said data having been encoded in at least one stream withat least a predetermined bit rate, said stream having been previouslycut into a plurality of segments.

According to the invention, said device comprises the following units,implemented for a segment of said at least one data stream:

-   -   Determination of at least one sub-segment size at least based on        the number of links and a size of the data stream to be        delivered;    -   Calculation of a partitioning of the segment into sub-segments        according to said at least one set size and a distribution of        the sub-segments over the plurality of links at least in        accordance with a scheduling of the sub-segments in the        partitioning calculated and a predetermined time constraint; and    -   Sending a plurality of transmission requests of the sub-segments        to the server over the plurality of links, at least according to        the distribution calculated, a transmission request of a        sub-segment over a link comprising at least one identifier of        the segment, an index of a sub-segment start and an index of a        sub-segment end.

Such a device can advantageously be integrated into a customer terminal.

The invention thus also relates to a customer terminal adapted to accessa communication network by at least two links according to distincttypes of access, comprising a device for processing a request for thedelivery of data according to the invention.

Alternatively, such a device can also be integrated into a proxy moduleadapted to be placed upstream of a client equipment. The inventiontherefore also relates to a proxy module arranged as cut-off system of acustomer terminal and of at least two links according to distinct typesof access for accessing a communication network, characterised in thatit comprises a device for processing a request for delivery of dataaccording to the invention.

The invention also relates to a computer program comprising instructionsfor implementing the steps of a method for processing a request fordelivery of a multimedia data stream as described above, when thisprogram is executed by a processor.

This program can use any programming language. They can be downloadedfrom a communication network and/or recorded on a computer-readablemedium.

Finally, the invention relates to a recording medium, readable by aprocessor, integrated or not integrated with the device for sending arequest for delivery of a multimedia data stream according to theinvention, possibly removable, respectively storing one computer programimplementing a method for processing a request for delivery of data, asdescribed above.

5. LIST OF FIGURES

Other advantages and characteristics of the invention will appear moreclearly on reading the following description of a particular embodimentof the invention, given by way of a simple illustrative and non-limitingexample and of the appended drawings, among which:

FIG. 1, already described, schematically shows the exchanges implementedby a client equipment with a server equipment for the delivery of amultimedia data stream in adaptive streaming, according to the priorart;

FIG. 2 schematically shows a client equipment having several accesslinks to a telecommunication network for requiring the delivery of amultimedia data stream to a server equipment, according to theinvention;

FIG. 3 schematically shows the steps of a method for processing arequest for delivery of a multimedia stream by a client equipmentaccording to an embodiment of the invention;

FIG. 4A schematically shows an exemplary structure of a sequence ofencoded images implemented in one embodiment of the invention;

FIG. 4B shows an example of quantities of encoded information to bedelivered per type of structure of images according to an encodingscheme of MPEG type;

FIGS. 5A, 5B and 5C illustrate schematically three examples ofdistribution of the sub-segments cut in a segment on the various accesslinks to the telecommunication network according to the invention;

FIG. 6 schematically shows a diagram of the streams exchanged between aclient equipment, a proxy module and a server equipment for the deliveryof a multimedia data stream according to an embodiment of the invention;

FIG. 7 illustrates using a mean latency curve, based on time, the stepof choosing a representation for the segment being delivered accordingto an embodiment of the invention;

FIG. 8 presents schematically an example of bit rate adaptation torespond to a predetermined delay constraint according to an embodimentof the invention; and

FIG. 9 schematically shows an example of a simplified structure of adevice for processing a request for delivery of a multimedia data streamaccording to the invention.

6. DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION

The general principle of the invention is based on the division of datasegments available from a server equipment into sub-segments of sizesdetermined by a client equipment at least based on the number of accesslinks to the telecommunication network available, on the performance ofeach of these links for example in terms of latency and bandwidth andthe size of the data stream to be delivered.

Such a cut-out reduces the transmission latency on each link andoptimises the use of the available bandwidth on the different links. Inrelation to FIG. 2, let us consider an exemplary backgroundimplementation of the invention. In particular, let us consider ancustomer equipment UE, such as a laptop, tablet or smart phone connectedto a telecommunication network RT, by a plurality of access links. Inthis example, the customer equipment UE has:

-   -   a wired link L1 to a home and company gateway-type access point        PA1;    -   a radio access link L2 to an access point PA2, of Wifi type        according to IEEE standard 802.11x; and    -   a radio access link L3 to an access point PA3, for example a        base station (“node-B” for 3G,“e-Node B” for 4G) of 3G, 4G-type        or future generation of the 3GPP standard.        For simplicity, a single telecommunication network RT has been        shown. Of course, this network can be composed of several access        networks, according to the access technologies which have just        been cited by way of example, WAN (for “Wide Access Network”) or        mobile to the IP network (for “Internet Protocol”).

By means of these various links, the customer equipment UE can connectto a server device ES, for example in a client-server mode, a web-basedtechnology and an http-type communication protocol to request thedelivery of a multimedia data stream made available by the serverequipment.

In the remainder of the description, the link is designated both by aparticular access Li to the telecommunication network RT available tothe customer terminal and the whole of the path followed by the dataexchanged by the customer terminal with the server equipment via thisparticular access.

In the following we consider that the customer equipment UE and theserver equipment ES are arranged to implement the adaptive streamingtechnology according to the MPEG-DASH standard.

Referring now to FIG. 3, the steps of a method for processing a requestfor delivery of multimedia data according to an embodiment of theinvention are described. The request for delivery of data has been sentby a customer equipment UE destined for a server equipment ES. It isconsidered that the method which will be described can be implemented bya device integrated in the client equipment itself or by a proxy moduleplaced in a cut-off between the links L1, L2, L3 for access to thenetwork and the customer equipment. The device according to theinvention is therefore arranged to intercept the request and to processit.

During a step E1, a request to describe the data to be delivered,transmitted by the client equipment and received by the device accordingto the invention, is transferred to the server equipment ES. Forexample, this request is of the “MPD request” type. In response, adescription file of type MPD is obtained. In a known manner, such a filedescribes the different segments of the multimedia data stream which areavailable at the server equipment ES in each of the possiblerepresentations of the same stream, each corresponding to a given bitrate, and therefore to a given quality. In particular, for a segment Sof a given representation, the description file comprises at least thesize of the segment and information on the location of this segment, forexample of the url type, in order to access the entire segment.

With the invention, it is also necessary to access informationrepresentative of the sub-segment positioning in the byte range, forexample a byte index of the start of a sub-segment and an index of theend of a sub-segment.

In the case of an “on-demand profile”, the MPEG-DASH standard uses anISO File Base File File Format (ISOBMFF), including an @SIDX address,requiring a detailed description, called SSIX (for “Sub Segment Index”)of an encoded structure of the segment S for a representation F(S). Thisdetailed description associates with positioning information, forexample a start index (in bytes) and an end index, a piece ofinformation representing a type of encoded information.

This profile has been designed to allow a client of a “video on demand”application to move in a segment of a data stream and perform read-only“Fast forward”-type functions. The implementation of such functionsrequires indeed to know the structure of the encoded data in order tolocate the positioning of the reference images I and to trigger the hopfrom one image I to another.

During a step E2, the device according to the invention thus requiresthe detailed description of the SSIX associated with the quality ofrepresentation F(S) of the segment S at the address @ SIDX obtained.

For example, in the case where the data stream represents an encodedvideo sequence, such a description provides information on the type ofimage encoded in the segment S and on a membership group of the encodeddata. According to a type of MPEG encoding scheme, for example, theimages of a sequence are grouped into GOP (for “Group of Pictures”).

According to one embodiment of the invention, a single description maybe required corresponding to a particular representation F(S). Accordingto another embodiment, several descriptions are required correspondingto several representations.

In relation to FIG. 4A, a typical example of a GOP structure comprisingimages of different types is presented: a reference image, called imageI, encoded independently of the other images, predicted images of typeP, encoded by prediction with respect to the reference image I andbidirectional type B images, predictively encoded with respect to twopast or future I, P or B images.

It is therefore understood that the description SSIX associates an imagetype and a membership group with data positioning information or byterange in the segment S for a given representation quality F(S).

Referring to FIG. 4B, an example of frame load FL is presented in termsof quantities of data encoded by image type FT of a GoP. This clearlyillustrates the fact that a reference image I represents a much greaterframe load than a P or B image and highlights the need to take fulladvantage of the available network resources in order to optimise thetransmission of the data of the image I on which all the other images ofthe GoP depend.

During a step E4, a size Ti of sub-segment per link Li of access to thenetwork RT available at the customer equipment UE is determined, with ian integer between 1 and the number of links, at least depending on thevolume of data of the segment to be delivered in the chosenrepresentation and the number of access links available.

A first simple embodiment of this step is to divide the size of thesegment to be delivered by the number of access links.

Advantageously, this step E4 also takes into account parametersrepresenting a state of the communication channel on each of theavailable access links. These parameters have, for example, beenpreviously measured during a previous delivery of another data stream orof a previous segment of the same data stream. They include for examplea measurement of latency time, a measurement of the transmission rate, ameasurement of a data loss rate or a jitter measurement, that is to saya measurement of transmission delay between two packs of requiredsimultaneously.

These parameters provide information about a link capacity considered totransmit a sub-segment in terms of download speed, hence delay,reliability, loss rate, etc. It is understood that these parametersaffect the size of a sub-segment. For example, for a link associatedwith a high latency, we shall determine a smaller sub-segment.

A sub-segment size for a link type takes into account the efficiency ofthe link, in terms of latency and bit rate. Latency is typicallydeducted from the RTT (for “Round Trip Time”); the effectiveness of alink Li is for instance shown as an effective weight Epi, which can beexpressed as follows:

$\begin{matrix}{{Epi} = {{66 \cdot \frac{bpi}{\sum\limits_{({1,n})}^{\;}{bpi}}} + {33 \cdot \frac{\min\left\lbrack {{RTT}\left( L_{1,N} \right)} \right\rbrack}{\min\left\lbrack {{RTT}({Li})} \right\rbrack}}}} & {{Eq}\mspace{14mu} 1}\end{matrix}$in which bpi means the measured bandwidth on the path corresponding tothe link Li and RTT(Li) the Round Trip Time of the link Li.This example gives a weight three times higher to the bit rate than tothe latency. The size of the sub-segment will then be calculatedaccording to a distribution algorithm, for example:Ti=TS×[Ep/ΣEpi], with TS the size of the segment.

Advantageously, this step E4 exploits the knowledge of the structure ofthe segment data obtained by E2. For example, it emphasizes the fact tocut the segment into sub-segments comprising data of one and the sametype, for easier processing of the sub-segments including their decodingphase. The aim is therefore to find a compromise between a sub-segmentsize that satisfies transmission constraints on a link and a size thatminimizes the number of “hybrid” segments that is to say, bringingtogether data of at least two different types.

At the end of step E4, a size Ti of a sub-segment was determined,adapted to each link Li to the network RT.

During a step E5, we use sub-segments of determined sizes to cut thesegment to be delivered into sub-segments and allocate the cutsub-segments on the different access links to the telecommunicationnetwork RT. This step takes into account a scheduling of sub-segments inthe segment to be delivered. Indeed, to be able to decode and playwithout waiting for the data stream as the sub-segments are received, wemust receive them in the correct order. Therefore, the requests forsub-segments should be allocated on each link so as to receive thesub-segments in accordance with their original scheduling in the segmentto be delivered.

At this stage, it is understood that the steps of determining sizes ofsub-segments, of cutting a segment into sub-segments of the specifiedsize(s) and of distributing the sub-segments obtained on the links Liare closely interwoven, particularly when determining a size per linkand when taking into account the structure of the encoded data in thesesteps.

In connection with FIGS. 5A and 5B, we find two examples of cutting asegment S into sub-segments with size T1 determined for the link L1, T2determined for the link L2, T3 determined for the link L3 and ofdistributing the sub-segments obtained on the three available links L1,L2, L3.

In the example in FIG. 5A, the segment S is cut successively into asequence of distribution which comprises a sub-segment SST1 with size T1which we will be queried on the link L1, a sub-segment SST2 with size T2to be queried on the link L2 and a sub-segment SST3 with size T3 to bequeried on the link L3.

In the example of FIG. 5B, the sizes T1, T2, T3 determined areidentical, but the distribution sequence is selected differently: twosuccessive sub-segments with size T1 are assigned to the link L1,followed by a sub-segment with size T2 attributed to the link L2 and asub-segment with size T3 attributed to the link L3.

Advantageously, this step also takes into account on the one hand theknowledge of the parameters representing a state of the communicationchannel on each of the links. Indeed, they are indicative of a level ofreliability of each link, of a bit rate, of a bandwidth etc. In otherwords, we shall ask more sub-segments in a link, for example L1 whichhas a higher bit rate than a link, L2 or L3 which has a lower bit rate.

Advantageously, this step E5 also takes into account the knowledge ofthe structure SSIX of the segment S, obtained in E2. Advantageously, apriority level was previously assigned to each type of data that may beincluded in a segment and this priority level is used to decide thedistribution of the segments on the different links.

By way of example, we again consider the case of a sequence of imagesorganised into GOP. It is understood that the type I reference imagesare very important for decoding the GOP because they are the basis fordecoding other images, among which only the residual error with respectto this reference image was transmitted in the data stream. It istherefore appropriate to assign a higher level of priority than theimages I than at the images P or B, with an image which might be interms of type of encoded image.

Advantageously, the step E5 also takes into account the knowledge of thestructure of the encoded data for cutting a segment into sub-segmentsand distribute the requests of sub-segments on the different links, forexample by associating a level of decoding priority to a sub-segmentbased on the type of data it contains.

In connection with FIG. 5C, the segment S first comprises type I dataand type P data. Suppose we assign a priority level 1 to type I data anda priority level 2 to type P images. The step E4 of distributingsub-segments on the links L1, L2, L3 available advantageously exploitsthis priority level and favours the links L1 and L2 which are morereliable to request the type I sub-segments. Conversely, it affects thetype P sub-segments to the link L3 considered as less reliable. During astep E6, sub-requests Sreq (SSn) for delivering sub-segments SSn of thesegment S are intended for the server equipment ES on the differentaccess links to the network RT, according to the distribution which hasjust been determined.

By way of example, we consider a 1 s-time segment composed of an imageIntra (I) of several hundreds of kilobytes (KB) of data followed byseveral Predicted images (P) of several tens of KB s and of severalbi-directional images or B of a few KB s. A maximum level of priority isassociated with the sub-segments SST11, SST22, SST12, SST22 and SST13that include the encoded data of the image I. They are distributed onthe most efficient links L1, L2 in terms of latency and bandwidth.

It is understood that this first distribution of sub-segments of theimage I is important because it determines the overall latency of thedelivery of the segment. In fact, the images P which are based on thedecoded image I are expected by the decoder of the client equipmentafter the arrival of the image Intra, we therefore have a little moretime to transmit, for example using a 3G mobile radio link; such as linkL3, which is less efficient in terms of bit rate and latency, but which,due to its constant bit rate, ensures the reliability of the transmitteddata.

As for images B, they are distributed on the different links followingthe sub-segments of the image I. Note that these images are lessimportant for decoding, since they do not serve as reference to anyother image of GoP. They are then associated with a lower prioritylevel. One option may be to decode them when transmitted to the clientequipment with the correct latency and to ignore them otherwise.

In a step E6, the sub-segments are requested on the links. We firstconsider that the sub-requests Sreq concern the first segment of thedata stream. If the determined distribution corresponds to the examplein FIG. 5A, a delivery sub-request of the first sub-segment SST1 istransmitted on the link L1, a delivery sub-request of the secondsub-segment SST2 is transmitted on the link L2, a delivery sub-requestof the second sub-segment SST3 is transmitted on the link L3.

Advantageously, these sub-requests are issued simultaneously on thethree links in order to optimise the use of available transmissionresources.

If the determined distribution corresponds to the example of FIG. 5B,the same delivery sub-request transmitted on the link L1 mayadvantageously involve several sub-segments, such as for example thefirst and second sub-segment SST11, SST12.

Upon making sub-requests, the process switches in E7 to await responsesfrom the server equipment ES.

In E8, it receives the first responses Resp(SSn) from the serverequipment. The process is then repeated for the next sequence ofsub-segments.

In E6, the transmission of sub-requests for delivery of sub-segments ofthe segment S can be managed in different ways. According to a firstaspect, a first burst of sub-requests is transmitted simultaneously onthe links, one sub-request per link. The system then waits for thereception of the required sub-segments before triggering thetransmission of new sub-requests. This type of management corresponds toa conventional mode.

Advantageously, a transmission mode of “burst” type (also calledpipelining http) can be implemented, which consists in furthertransmitting on the same link a series of requests of sub-segments, asubsequent request is issued before having received the response of theprevious request. In a real-time reception context, this type ofmanagement, as it seeks maximum transmission and processing resourcesfrom the server, enables to optimise the transmission time.

For example, one might consider issuing in a burst mode all thesub-requests of sub-segments assigned to a link in the distributionstage, this mode can nevertheless being switched on solely whenreal-time operation is becoming a problem for example in the case of a“heavy” image Intra which is a large data file and that despite thesmall buffer of the decoder (eg 40 ms buffer) may cause the arrival ofother images and the loss of the live clock, and in this case fasterdownloading the following images with this burst mode makes perfectsense.

Conversely when everything unfolds almost synchronously, a sequentialmode may prove sufficient.

Whatever the transmission mode of sub-requests used, the process starts,following the issuance of one or more sub-requests on a link, a step E9of measuring a latency time between TL the issuance of a sub-request andthe reception of a response to the sub-request on the link. Moregenerally, this step E9 measure other parameters representative of thenetwork status on the links L1, L2, L3 and updates the parameterspreviously used to determine a particular sub-segment size for eachlink. We understand that these new measurements are particularlyinstructive since they concern the transmission of sub-segments whosesize was determined to be the most adapted as possible to thetransmission conditions on a link. They are used to verify that it isoptimal and that the delay constraint CD is respected.

Advantageously, the method includes a step E3 of choosing arepresentation for the segment being delivered. This step uses thenetwork parameters measurements carried out in E9, especially themeasurement of the latency time TL. Initially, the customer terminal hasrequested the segment S in a particular representation. Then, if thedelay constraint CD is violated, or conversely if the network conditionsare favourable, the step E3 enables to decide to change representationbefore the end of the delivery of the current segment. If the constraintis exceeded, it will choose a lower bit rate of representation, thusless costly in terms of bandwidth. On the contrary, if the measuredlatency is less than the constraint, it chooses to move to a higher bitrate representation to optimise the quality of the delivered data.

The invention allows to adapt to changing network conditions with afiner granularity than the segment.

Of course, we understand that it is not always well-advised to changerepresentation anywhere in the same GoP. In particular, the aim is totake into account the information regarding membership to a group aswell as type of data obtained during the step E2. Indeed, thesub-segments corresponding to an image P or B which depend on areference image I should be extracted from the same representation asthe sub-segments corresponding to this image I, so that the decoding ispossible at the customer equipment.We understand that it will be possible to change the representation fromthe image I below. The invention thus enables to track the delayconstraint with an intra to intra granularity.

Advantageously, the process then repeats the step E4 of determining asize of a sub-segment per link from the new network parametermeasurements and the step E5 of cutting the segment and of distributingsub-segments on the links, according to new and updated measurements ofnetwork parameters and sub-segment sizes.

In this way, we change the structure of real time sub-requests to adaptto the actual conditions of transmission on different links.

Of course, depending on the size of a segment, it is possible to applythe updates calculated at the next segment, which seems a goodcompromise between complexity and adaptability. In this way, thestructure and distribution of sub-requests for a current segment arebased on measurements made during the delivery of the previous segment.

To minimize the overall delay of transmission of data segments, themethod according to the invention suggests to control the maximumquality of the segments delivered for a predetermined latency setpoint.For example, a live delay is set to 70 ms and the method calculates thecorresponding downloading times for each of the available encodinglevels (adaptive bit rate) and chooses the optimal representation.

When the latency time TL measured for a sub-request exceeds apredetermined threshold, for instance 70 ms (which includes the RTT,that is to say the delay between the transmission of a rising httprequest and the reception in return from the first bit data which isadded the download time. For example, on a network with a RTT of 30 ms,there remain 40 ms to download the data), while no response to asub-request has been received, a step E10 is implemented during which itis decided to undertake an action to remedy this problem. Severalactions can be taken.

This decision step can advantageously take into account the knowledge ofthe structure of the segment obtained in Step E2, and in particular thepriority level that was associated with the sub-segment(s) not received.This priority level provides valuable information to decide whether thereceipt of this sub-segment is important for the decoding of the datastream or if the contrary, we can do without it, with the risk of animage quality which may be locally and temporarily degraded.

If the reception of this sub-segment is considered significant, forexample because it is associated with a high priority level, it may bedecided to renew the broadcast of the sub-request on another, morereliable link. It is understood that, due to the real time constraintassociated with the delivery of the data stream segment, it is notpossible to wait for delivery of the failing link beyond a predeterminedlimit.

If the reception of this sub-segment is not considered necessary, adecision may be to do nothing and decode the segment without the missingsub-segment.

At this stage, we consider a particular embodiment of the invention inwhich the customer equipment is an MPEG-DASH customer and the mode ofcommunication used between the customer equipment CE and the serverequipment SE complies with HTTP (for “Hypertext Transfer Protocol”) overTCP (for “Transmission Control Protocol”). According to the latterprotocol, the customer equipment and the server equipment previouslyestablish a communication session during which the customer equipmentcan issue a delivery request to the equipment server. Once it hasreceived the reply to its request the customer equipment acknowledgesreceipt to the server equipment. Until it has received acknowledgmentfrom the customer equipment, the server equipment regularly retransmitsthe response to the request of the customer equipment. It is understoodthat this protocol ensures communication of data between the two piecesof equipment, but in case of transmission problem, the retransmissionmechanism generates traffic and latency on the link that is littlecompatible with real time problems.

In this context, the step E10 can advantageously decide to cancel onehttp sub-request that does not receive a response on a link within theset time. In the previous embodiment, the cancellation action isinteresting for images, i.e. non-priority sub-segments. It includes theclosure of the current session with the server equipment on the relevantlink. The interest of this cancellation is to stop trafficking andsignalling such as the protocol TCP generated between the customerequipment and the server equipment that occupy the resources of thesetwo pieces of equipment.

Alternatively, rather than cancel the sub-request in progress, it may bedecided to systematically issue an acknowledgment of the response, evenif it has not been received. The effect generated on the serverequipment side will be the same as before, namely the closure of thecurrent session.

We understand that it may be decided to carry out several actionssimultaneously, for instance, cancel an existing sub-request on a link,to end the traffic generated by its processing and to renew the issuanceof this sub-request on another link, considered more reliable to limitthe delay in receiving the full segment.

In E11, the segment is reconstructed from the received sub-segments thentransmitted in E12 to the customer equipment UE in response to itsinitial request.

The steps of the method are then repeated for the next segment of thestream data.

In connection with FIG. 6, we consider, by way of example the case of afirst customer equipment having a wired access L0 to the network RT witha bit rate of 12 Mb/s. The first image I requires 266 ms in order to bedelivered. Real time latency delay LDL is 266 ms. The other images aresmall and transmitted in less than 30 ms. It is not effective tosub-segment them further.

Then we consider the case of a second customer equipment having 4 wiredaccesses L′1 to the L′4 of ADSL type (for “Asymmetric Digital SubscriberLine”) and a mobile access 4G L′5, and implementing the method accordingto the invention. The image I corresponds to a volume of data of 400 KB.It is divided into five sub-segments of different sizes to be requestedfor each of the 5 links, depending on the effectiveness Epi of eachlink, which may, as an example, be calculated from one of the followingequations:

-   -   in the case where the access links are very close in terms of        latency but have bit rate deviations:

$\begin{matrix}{{Epi} = {{66 \cdot \frac{bpi}{\sum\limits_{({1,n})}^{\;}{bpi}}} + {33 \cdot \frac{\min\left\lbrack {{RTTp}\left( {1,n} \right)} \right\rbrack}{\min\left\lbrack {{RTT}({pi})} \right\rbrack}}}} & \left( {{Eq}\mspace{14mu} 1} \right)\end{matrix}$

-   -   in the case where the access links are very heterogeneous in        terms of latency:

$\begin{matrix}{{Epi} = {{66 \cdot \frac{bpi}{\sum\limits_{({1,n})}^{\;}{bpi}}} + {33 \cdot \frac{\left( {1 - {{{RRT}({pi})}/{\sum{\left( {1,n} \right){{RTT}({pi})}}}}} \right.}{\left( {p - 1} \right)}}}} & \left( {{Eq}\mspace{14mu} 2} \right)\end{matrix}$The size of a sub-segment adapted to the link L′i is calculated asfollows, depending on the effectiveness Epi of the link L′i:

$\begin{matrix}{{T^{\prime}i} = {{TF} \cdot \frac{Epi}{\sum\limits_{({1,n})}^{\;}{Epi}}}} & \left( {{Eq}.\mspace{14mu} 3} \right)\end{matrix}$with T_(F) the size of the current image to be downloaded the segment S.

In this way, uploading an image T_(F) is apportioned on the differentlinks L′i available according to their respective efficiencies.

Thus the data sub-segment corresponding to a complete Intra image willbe downloaded in parallel on the links of different efficiency in termsof bit rate and of latency:

-   -   for the link L′1 having a bit rate equal to 14 Mbps, an RTT        equal to 21 ms and an efficiency        Ep=66×14/72+33×[(145−21)/145]/4=20, a size of sub-segment is        determined as equal to 80 KB;    -   for the link L′2 having a bit rate equal to 11 Mbps, an RTT        equal to 27 ms and an efficiency        Ep=66×11/72+33×[(145−27)/145]/4=17, a size of sub-segment is        determined as equal to 68 KB;    -   for the link L′3 having a bit rate equal to 5 Mbps, an RTT equal        to 31 ms and an efficiency Ep=66×5/72+33×[(145−31)/145]/4=11,        the size of sub-segment is determined as equal to 44 KB;    -   for the link L′4 having a bit rate equal to 7 Mbps, an RTT equal        to 36 ms and an efficiency Ep=66×7/72+33×[(145−36)/145]/4=13, a        size of sub-segment is determined as equal to 52 KB;    -   for the link L′5 having a bit rate equal to 35 Mbps, an RTT        equal to 30 ms and an efficiency equal to Ep=66×35/72        33×[(145−30)/145]/4=39, a size of sub-segment is determined as        equal to 1562 KB.

We understand that with the invention each link has a contribution interms of volume of data provided to the delivery of data for itsperformance in download time measured from the network parameters. Thedownload times of the various sub-segments on the links will depend onthe nature of the link (latency and bandwidth).

Experimentally for the 5 links given in the example, we obtain for theL′1 a download time of 68 ms, for the link L′2 a time of 74 ms, for L′3a time of 105 ms, for L′4 a time of 89 ms and for L'S a time of 54 ms.

The largest sub-segment is delivered in 105 ms. As a result, thereal-time latency time LDL is reduced to 105 ms.

In the example described in connection with FIG. 7, we consider anotherexample in which the server equipment ES offers 4 performances or datastreams for the same content:

-   -   a stream F1 encoded at 500 kbps;    -   a stream F2 encoded at 1000 kbps;    -   a stream F3 encoded at 2000 kbps; and    -   a stream F4 encoded at 3500 kbps.

There is shown in the same figure a plot LTM of the average latency ofthe various network links based on the time and representation as astaircase of the representation qualities selected by the deviceaccording to the invention over time.

To satisfy a predetermined delay constraint CD, in this example equal to70 ms, the method according the invention selects, in a step E3, arepresentation at a bit rate BR among those available (F1 to F4), e.g.F1 at 500 Kbps; to request the first sub-segments. This choice takesinto account not only the delay constraint CD, but also the networksconditions. In this example, we see that the playback of the encodeddata is started at quality F1, the lowest available, which enables toinitiate the playback by ensuring the delay setpoint. For the followingGoP, we switch to the quality F3, which is higher and respects thesetpoint. This regime lasts during the transmission of multiple GOPsuntil the appearance of network problem, and in response to an average,increasing latency, we come down to the quality F2. Then, given that theaverage latency measured drops, it switches to a representation F4 ofhigher quality.

In connection with FIG. 8, it now presents a diagram of the streamsexchanged between a customer equipment UE, a proxy module MP and aserver equipment ES according to an exemplary embodiment of theinvention. In this example the module MP placed upstream of the customerequipment UE, implements the method of processing a delivery request ofa data stream according to the invention which has just been describedin connection with FIG. 3. This module has access to different links L1,L2, L3, available to the customer equipment. In this example, thecustomer equipment UE complies with the MPEG-DASH standard and itsoperation is not affected by the invention.

In a known manner, the customer equipment UE sends a request “MPDRequest” for a description of a data stream FD to the server equipmentES on one of its links L1, L2 or L3 for accessing the network RT. In E1,the request is relayed transparently by the proxy module MP andtransmitted to the server equipment ES.

The server equipment ES responds by transmitting the correspondingdescription file MPD.

In a known manner, the customer terminal UE requests the delivery of asegment S of the data stream to the server ES by issuing a type of httprequest Req (S) on the same link Li as previously.

This request is intercepted by the proxy module MP, which transmits inE2 a request “Sidx Request” describing the segment S at the server ES onone of the links available, for instance the link Li chosen by thecustomer UE.

In response, the server ES transmits the description file SIDX (SSIX) ofthe segment S.

In E3, the proxy module can choose a representation to request thesegment S. At first, it usually chooses the one that has been requestedby the customer terminal.

From the information contained in this file regarding the structure ofmultimedia data encoded in the segment S for each of the representationsand the knowledge of representative parameters of a network status onthe links available, the proxy module determines in E4 a sub-segmentsize adapted to every link Li.

Then, in E5, the proxy module MP cuts the segment S into sub-segments ofdefined sizes and distributes them on the different links.

In E6, it transmits the first sub-requests S-Req(SSn, Li) on thedifferent links. In E7, it switches into waiting mode for receivinginitial responses.

The ES server, upon receipt of sub-requests Sreq(SSn, Li) transmitsresponses including the sub-segments SSn requested on the links Liconcerned. Then it waits for an acknowledgment from the customer UE.

In E8, the module MP receives the first responses S-Rep(SSn, Li), itstores them in memory, for example in a buffer.

Upon receipt of the first responses, it updates in E9 the measurementsof the network parameters, particularly the latency time TL of the linksconcerned.

Advantageously, the steps E3, E4 and E5 are repeated to take intoaccount the new measurements of network parameters and optimise thechoice of representation, the sub-segment sizes and the distribution ofsub-segments on each link.

Advantageously, the sub-segments corresponding to a priority image Intraare requested repeatedly on different links measured as very effective.According to this option, the proxy module takes into account on theproxy side only the sub-segments arrived first. One advantage is toavoid retransmissions that may not be achievable any longer in thepredetermined time set.

If after a predetermined latency time, sub-segments have not beenreceived, the proxy module decides in E10 about an action to trigger forremedying purposes, for example to request the sub-segment on anotherlink, cancel the current request etc.

The request step E6 is iterated to request the following sub-segments.As described above, different strategies can be implemented. Forexample, the proxy module MP expects to have received previoussub-segments on the different links to request the following ones, whichcan take into account new measurements of network parameters and thusoptimise the use of resources of the different links. An alternative isto require the sub-segments assigned to a given link in burst mode,without waiting for the first sub-segments. One advantage is to minimiselatency on the link as far as possible. However, the optimisation of thedistribution may be implemented only for the next segment.

Once it has received all the possible sub-segments from the segment S,the module MP reconstructs the sub-segment E11 and transmits it to thecustomer EU in E12 as a response http Rep(S) according to the standardMPEG-DASH.

According to the communication protocol used, the customer terminal UEmay acknowledge receipt of the segment S required. In this case, theproxy module MP does not transmit the acknowledgment message to theserver ES.

It is understood that according to this embodiment, the customerequipment UE can continue to function in a normative way, whilebenefiting from optimised delivery, which operates all the linksavailable to access the telecommunication network.

Note that the invention which has just been described, can beimplemented using software and/or hardware components. In this context,the terms “module” and “entity” used in this document, can correspondeither to a software component or a hardware component or even a set ofhardware and/or software components, capable to implement thefunction(s) outlined for the module or entity concerned.

FIG. 9 schematically shows an example of a simplified structure of adevice 100 for sending a request for delivery of a multimedia datastream according to the invention. The device 100 implements the methodfor sending a request for delivery of multimedia data stream accordingto the invention which has just been described in relation to FIG. 3.

For example, the device 100 includes a processing unit 110, equippedwith a processor μ1 and driven by a computer program Pg1 120, stored ina memory 130 and implementing the process according to the invention.

At initialisation, the code instructions of the computer program Pg1 120are for example loaded into a RAM memory before being executed by theprocessor of the processing unit 110. The processor of the processingunit 110 implements the steps of the method described above, accordingto the instructions of the computer program 120.

In this embodiment of the invention, the device 100 includes at leastone unit 111 for obtaining a description file of the data stream, a unit112 for determining a size of sub-segment by link to access the networkRT, a unit 113 partitioning a segment S into sub-segments based on thedetermined size, a unit 114 for transmitting a sub-request of asub-segment on a link Li and a unit 115 for receiving the sub-segmentSSn required.

Advantageously, the device 100 comprises a unit 116 for obtaining astructure of the data segment S, a unit 117 for measuring the statusparameters of the network on the links L1, L2, L3, a unit 118 forselecting a representation of the segment S, a unit 119 for deciding totrigger an action when the sub-segment has not been received after apredetermined latency and a segment RECONST S for reconstructing of thesegment S once all the sub-segments were received.

The device 100 further comprises a unit BD1 for storing the sub-segmentsreceived. This is for example a small buffer to firstly wait for thecompleteness of an arriving image and secondly to have a slight timebuffer to ensure the timing of the decoding. In the implementationprocess, 40 ms are enough to induce a delay of 0 to 40 ms. An importantissue concerns the reception of sub-segments by a device 100 integratedto the proxy described above, it endeavours to order the sub-segmentsfor transmission to the customer DASH, but does not reconstitute thefull image before transmitting it to the customer, which will inevitablyincrease the overall delay. These units are driven by the processor μ1of the processing unit 110.

Advantageously, such a device 100 may be integrated to a customerterminal CT or a proxy module MP located upstream of a customerequipment according to the prior art. One advantage of such a proxymodule is that it can implement the invention from a customer equipmentalready on the market, without the need to modify the operation of thecustomer equipment. The device 100 is then arranged to cooperate with atleast the following modules of the customer terminal UE or of the proxymodule MP:

-   -   a module E/R for transmitting/receiving data via queries are        transmitted in the telecommunication network RT to the server        equipment ES, such as various links L1, L2, L3 accessible at the        customer equipment UE, such as a wired WAN access network or a        wireless Wifi access network or still a 3G, 4G mobile network or        a next generation of standard 3GPP;    -   a module DEC for decoding encoded data contained in the        sub-segments received by the customer equipment UE or the proxy        module MP.

The invention that has just been presented finds numerous applicationsinvolving the delivery of data, for example multimedia, with timeconstraints, up to real time applications. Indeed, on the customer'sside, the method of processing a request for delivery according to theinvention is capable of organising the delivery of data by optimisingthe bit rate and the available network resources while meeting a “timeto live” target. By way of example, it could be used to implement anonline voting service (“video-voting”), cloud gaming or evenvideoconferencing.

An exemplary embodiment of the invention improves the situationdescribed above with respect to the prior art.

An exemplary embodiment in particular overcomes the shortcomings of theprior art described above.

Specifically, an exemplary embodiment of the invention provides asolution that delivers real-time multimedia data, that is to say withlatency constraints close to those of conversational services, whileretaining the benefits of adaptive streaming DASH technology,particularly in terms of deployment cost.

It goes without saying that the embodiments which have been describedabove have been given purely by an indicative and non-limiting way, andthat many modifications can be easily made by those skilled in the artwithout departing from the scope of the invention.

The invention claimed is:
 1. A method comprising: processing a requestfor delivery of data sent by a customer terminal to a remote serverequipment via a telecommunication network, said terminal being adaptedto access said network through a plurality of links, each of the linksproviding a distinct access path between the terminal and the networkaccording to a distinct access type, said data having been encoded in atleast one stream with at least a predetermined bit rate, said streamhaving been previously cut into a plurality of segments, whereinprocessing comprises the following acts, implemented by at least oneprocessing device for a segment of the at least one data stream:determining at least one sub-segment size at least based on a number ofthe links and a size of the data stream to be delivered; calculating apartitioning of the segment into sub-segments according to at least oneset size and a distribution of the sub-segments over the plurality oflinks at least in accordance with a scheduling of the sub-segments inthe partitioning calculated and a predetermined time constraint; andsending a plurality of transmission requests of the sub-segments to theserver over the plurality of links, at least according to thedistribution calculated, a transmission request of a sub-segment over alink comprising an index of a sub-segment start, an index of asub-segment end and at least one identifier of the segment.
 2. Themethod for processing a request for the delivery of data according toclaim 1, comprising an act of measuring parameters representative of anetwork state over the plurality of links, implemented upon receivingsub-segments from the server on said links in response to thetransmission requests and an act of updating the acts of determining asub-segment size per link and calculating a partitioning and adistribution of the sub-segments over the links according to themeasured parameters.
 3. The method for processing a request for thedelivery of data according to claim 2, comprising an act of determininga frequency for transmitting the requests over a link according to themeasured network parameters and wherein the transmission requests of thesub-segments over said link are sent at the determined transmissionfrequencies.
 4. The method for processing a request for the delivery ofdata according to claim 1, comprising an act of obtaining an encodingstructure comprising at least one piece of information representative ofa type of data encoded in the segment associated with positioninformation of the data of this type, an act of assigning a decodingpriority level to the sub-segments of a segment according to the typeinformation and to predetermined rules, and wherein the act ofpartitioning the segment into sub-segments and the act of distributingthe sub-segments over the plurality of links also take into account thelevels of decoding priorities assigned to the sub-segments.
 5. Themethod for processing a request for the delivery of data according toclaim 4, wherein the information representative of a type of data isobtained by sending a request for description of the segment to theserver equipment and by receiving a description file of an encodingstructure of the segment comprising said information.
 6. The method forprocessing a request for the delivery of data according to claim 4,wherein the act of measuring network parameters comprises measuring alatency time between the sending of a transmission request of at leastone sub-segment over a link and a reception of the requested sub-segmentand wherein said method comprises, when a latency time is greater than apredetermined threshold for said request, a decision act triggering anaction at least as a function of a priority level of decoding assignedto the requested sub-segment, said action belonging to a groupconsisting of: retransmitting a new transmission request from the samesub-segment to another link; and cancelling the current request.
 7. Themethod for processing a request for the delivery of data according toclaim 6, wherein the customer terminal and the server equipment arearranged to communicate according to a communication protocol withacknowledgment exchange, wherein when the action decided is acancellation of the current request, the method comprises an act oftransmitting an acknowledgment message to the server.
 8. The method forprocessing a request for the delivery of data according to claim 5,wherein the received description file further comprises informationrepresentative of a data membership group and at least one first encodeddata stream being available at a first bit rate and a second stream at asecond bit rate, and wherein the method comprises an act of selecting astream in which a sub-segment of a current segment can be requested, atleast based on measured network parameters, the decoding priority levelof the subset of the membership group of data of the sub-segment and thepredetermined time constraint.
 9. A device for processing a request fordelivery of data sent by a customer terminal to a remote serverequipment via a telecommunication network, said terminal being adaptedto access said network through a plurality of links, each of the linksproviding a distinct access path between the terminal and the networkaccording to a distinct access type, said data having been encoded in atleast one stream with at least a predetermined bit rate, said streamhaving been previously cut into a plurality of segments, said devicecomprising: a non-transitory computer-readable medium comprisinginstructions stored thereon; a processor configured by the instructionsto perform the following acts, implemented for a segment of said atleast one data stream: determining at least one sub-segment size atleast based on a number of the links and a size of the data stream to bedelivered; calculating a partitioning of the segment into sub-segmentsaccording to at least one set size and a distribution of thesub-segments over the plurality of links at least in accordance with ascheduling of the sub-segments in the partitioning calculated and apredetermined time constraint; and sending a plurality of transmissionrequests of the sub-segments to the server over the plurality of links,at least according to the distribution calculated, a transmissionrequest of a sub-segment over a link comprising at least one identifierof the segment, an index of a sub-segment start and an index of asub-segment end.
 10. A customer terminal comprising the device forprocessing according to claim
 9. 11. A proxy module arranged to cut offthe customer terminal and the plurality of links to access thecommunications network, wherein the proxy module comprises the devicefor processing according to claim
 9. 12. A non-transitorycomputer-readable recording medium, comprising a computer program storedthereon and having instructions for implementing a method for processinga request for delivery of data when executed by a processor, wherein theinstructions configure the processor to perform acts comprising:processing the request for delivery of data sent by a customer terminalto a remote server equipment via a telecommunication network, saidterminal being adapted to access said network through the plurality oflinks, each of the links providing a distinct access path between theterminal and the network according to a distinct access type, said datahaving been encoded in at least one stream with at least a predeterminedbit rate, said stream having been previously cut into a plurality ofsegments, wherein processing comprises the following acts, implementedfor a segment of the at least one data stream: determining at least onesub-segment size at least based on a number of the links and a size ofthe data stream to be delivered; calculating a partitioning of thesegment into sub-segments according to at least one set size and adistribution of the sub-segments over the plurality of links at least inaccordance with a scheduling of the sub-segments in the partitioningcalculated and a predetermined time constraint; and sending a pluralityof transmission requests of the sub-segments to the server over theplurality of links, at least according to the distribution calculated, atransmission request of a sub-segment over a link comprising at leastone identifier of the segment, an index of a sub-segment start and anindex of a sub-segment end.